Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
b=[["#"]*(w+2)]
a=0
for i in range(h):
  c=["#"]
  for j in input():
    a+=j=="#"
    c.append(j)
  b.append(c+["#"])
b+=[["#"]*(w+2)]
b[h][w]=0
Q=[(1,1)]
x=0
y=-1
while Q:
	x+=1
	p=[]
	for i,j in Q:
		for dx,dy in [(1,0),(-1,0),(0,1),(0,-1)]:
			if b[i+dx][j+dy]==".":
				p+=[(i+dx,j+dy)]
				b[i+dx][j+dy]="#"
			elif b[i+dx][j+dy]==0:
				y=x
	if y>0:break
	Q=p
if y>0:print((h*w)-a-y-1)
else:print(-1)